/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#if !defined(BITBOARD_H_INCLUDED)
+#ifndef BITBOARD_H_INCLUDED
#define BITBOARD_H_INCLUDED
+#include <algorithm>
+#include <cassert>
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <string>
+
#include "types.h"
-namespace Bitboards {
+namespace Stockfish {
-extern void init();
-extern void print(Bitboard b);
+namespace Bitboards {
+void init();
+std::string pretty(Bitboard b);
+
+} // namespace Stockfish::Bitboards
+
+constexpr Bitboard FileABB = 0x0101010101010101ULL;
+constexpr Bitboard FileBBB = FileABB << 1;
+constexpr Bitboard FileCBB = FileABB << 2;
+constexpr Bitboard FileDBB = FileABB << 3;
+constexpr Bitboard FileEBB = FileABB << 4;
+constexpr Bitboard FileFBB = FileABB << 5;
+constexpr Bitboard FileGBB = FileABB << 6;
+constexpr Bitboard FileHBB = FileABB << 7;
+
+constexpr Bitboard Rank1BB = 0xFF;
+constexpr Bitboard Rank2BB = Rank1BB << (8 * 1);
+constexpr Bitboard Rank3BB = Rank1BB << (8 * 2);
+constexpr Bitboard Rank4BB = Rank1BB << (8 * 3);
+constexpr Bitboard Rank5BB = Rank1BB << (8 * 4);
+constexpr Bitboard Rank6BB = Rank1BB << (8 * 5);
+constexpr Bitboard Rank7BB = Rank1BB << (8 * 6);
+constexpr Bitboard Rank8BB = Rank1BB << (8 * 7);
+
+extern uint8_t PopCnt16[1 << 16];
+extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
+
+extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
+
+
+// Magic holds all magic bitboards relevant data for a single square
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+
+ // Compute the attack's index using the 'magic bitboards' approach
+ unsigned index(Bitboard occupied) const {
+
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
+
+ if (Is64Bit)
+ return unsigned(((occupied & mask) * magic) >> shift);
+
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ }
+};
+
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
+
+inline Bitboard square_bb(Square s) {
+ assert(is_ok(s));
+ return (1ULL << s);
}
-CACHE_LINE_ALIGNMENT
-
-extern Bitboard RMasks[64];
-extern Bitboard RMagics[64];
-extern Bitboard* RAttacks[64];
-extern unsigned RShifts[64];
-
-extern Bitboard BMasks[64];
-extern Bitboard BMagics[64];
-extern Bitboard* BAttacks[64];
-extern unsigned BShifts[64];
-
-extern Bitboard SquareBB[64];
-extern Bitboard FileBB[8];
-extern Bitboard RankBB[8];
-extern Bitboard AdjacentFilesBB[8];
-extern Bitboard ThisAndAdjacentFilesBB[8];
-extern Bitboard InFrontBB[2][8];
-extern Bitboard StepAttacksBB[16][64];
-extern Bitboard BetweenBB[64][64];
-extern Bitboard ForwardBB[2][64];
-extern Bitboard PassedPawnMask[2][64];
-extern Bitboard AttackSpanMask[2][64];
-extern Bitboard PseudoAttacks[6][64];
-
-
-/// Overloads of bitwise operators between a Bitboard and a Square for testing
-/// whether a given bit is set in a bitboard, and for setting and clearing bits.
-
-inline Bitboard operator&(Bitboard b, Square s) {
- return b & SquareBB[s];
-}
-inline Bitboard& operator|=(Bitboard& b, Square s) {
- return b |= SquareBB[s];
-}
+// Overloads of bitwise operators between a Bitboard and a Square for testing
+// whether a given bit is set in a bitboard, and for setting and clearing bits.
-inline Bitboard& operator^=(Bitboard& b, Square s) {
- return b ^= SquareBB[s];
-}
+inline Bitboard operator&(Bitboard b, Square s) { return b & square_bb(s); }
+inline Bitboard operator|(Bitboard b, Square s) { return b | square_bb(s); }
+inline Bitboard operator^(Bitboard b, Square s) { return b ^ square_bb(s); }
+inline Bitboard& operator|=(Bitboard& b, Square s) { return b |= square_bb(s); }
+inline Bitboard& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); }
-inline Bitboard operator|(Bitboard b, Square s) {
- return b | SquareBB[s];
-}
+inline Bitboard operator&(Square s, Bitboard b) { return b & s; }
+inline Bitboard operator|(Square s, Bitboard b) { return b | s; }
+inline Bitboard operator^(Square s, Bitboard b) { return b ^ s; }
-inline Bitboard operator^(Bitboard b, Square s) {
- return b ^ SquareBB[s];
-}
+inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
+constexpr bool more_than_one(Bitboard b) { return b & (b - 1); }
-/// more_than_one() returns true if in 'b' there is more than one bit set
-inline bool more_than_one(Bitboard b) {
- return b & (b - 1);
-}
+// rank_bb() and file_bb() return a bitboard representing all the squares on
+// the given file or rank.
+constexpr Bitboard rank_bb(Rank r) { return Rank1BB << (8 * r); }
-/// rank_bb() and file_bb() take a file or a square as input and return
-/// a bitboard representing all squares on the given file or rank.
+constexpr Bitboard rank_bb(Square s) { return rank_bb(rank_of(s)); }
-inline Bitboard rank_bb(Rank r) {
- return RankBB[r];
-}
+constexpr Bitboard file_bb(File f) { return FileABB << f; }
-inline Bitboard rank_bb(Square s) {
- return RankBB[rank_of(s)];
-}
+constexpr Bitboard file_bb(Square s) { return file_bb(file_of(s)); }
-inline Bitboard file_bb(File f) {
- return FileBB[f];
-}
-inline Bitboard file_bb(Square s) {
- return FileBB[file_of(s)];
+// Moves a bitboard one or two steps as specified by the direction D
+template<Direction D>
+constexpr Bitboard shift(Bitboard b) {
+ return D == NORTH ? b << 8
+ : D == SOUTH ? b >> 8
+ : D == NORTH + NORTH ? b << 16
+ : D == SOUTH + SOUTH ? b >> 16
+ : D == EAST ? (b & ~FileHBB) << 1
+ : D == WEST ? (b & ~FileABB) >> 1
+ : D == NORTH_EAST ? (b & ~FileHBB) << 9
+ : D == NORTH_WEST ? (b & ~FileABB) << 7
+ : D == SOUTH_EAST ? (b & ~FileHBB) >> 7
+ : D == SOUTH_WEST ? (b & ~FileABB) >> 9
+ : 0;
}
-/// adjacent_files_bb takes a file as input and returns a bitboard representing
-/// all squares on the adjacent files.
-
-inline Bitboard adjacent_files_bb(File f) {
- return AdjacentFilesBB[f];
+// Returns the squares attacked by pawns of the given color
+// from the squares in the given bitboard.
+template<Color C>
+constexpr Bitboard pawn_attacks_bb(Bitboard b) {
+ return C == WHITE ? shift<NORTH_WEST>(b) | shift<NORTH_EAST>(b)
+ : shift<SOUTH_WEST>(b) | shift<SOUTH_EAST>(b);
}
+inline Bitboard pawn_attacks_bb(Color c, Square s) {
-/// this_and_adjacent_files_bb takes a file as input and returns a bitboard
-/// representing all squares on the given and adjacent files.
-
-inline Bitboard this_and_adjacent_files_bb(File f) {
- return ThisAndAdjacentFilesBB[f];
+ assert(is_ok(s));
+ return PawnAttacks[c][s];
}
+// Returns a bitboard representing an entire line (from board edge
+// to board edge) that intersects the two given squares. If the given squares
+// are not on a same file/rank/diagonal, the function returns 0. For instance,
+// line_bb(SQ_C4, SQ_F7) will return a bitboard with the A2-G8 diagonal.
+inline Bitboard line_bb(Square s1, Square s2) {
-/// in_front_bb() takes a color and a rank or square as input, and returns a
-/// bitboard representing all the squares on all ranks in front of the rank
-/// (or square), from the given color's point of view. For instance,
-/// in_front_bb(WHITE, RANK_5) will give all squares on ranks 6, 7 and 8, while
-/// in_front_bb(BLACK, SQ_D3) will give all squares on ranks 1 and 2.
+ assert(is_ok(s1) && is_ok(s2));
-inline Bitboard in_front_bb(Color c, Rank r) {
- return InFrontBB[c][r];
+ return LineBB[s1][s2];
}
-inline Bitboard in_front_bb(Color c, Square s) {
- return InFrontBB[c][rank_of(s)];
-}
+// Returns a bitboard representing the squares in the semi-open
+// segment between the squares s1 and s2 (excluding s1 but including s2). If the
+// given squares are not on a same file/rank/diagonal, it returns s2. For instance,
+// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5, E6 and F7, but
+// between_bb(SQ_E6, SQ_F8) will return a bitboard with the square F8. This trick
+// allows to generate non-king evasion moves faster: the defending piece must either
+// interpose itself to cover the check or capture the checking piece.
+inline Bitboard between_bb(Square s1, Square s2) {
-/// between_bb returns a bitboard representing all squares between two squares.
-/// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
-/// square d5 and e6 set. If s1 and s2 are not on the same line, file or diagonal,
-/// 0 is returned.
+ assert(is_ok(s1) && is_ok(s2));
-inline Bitboard between_bb(Square s1, Square s2) {
- return BetweenBB[s1][s2];
+ return BetweenBB[s1][s2];
}
+// Returns true if the squares s1, s2 and s3 are aligned either on a
+// straight or on a diagonal line.
+inline bool aligned(Square s1, Square s2, Square s3) { return line_bb(s1, s2) & s3; }
-/// forward_bb takes a color and a square as input, and returns a bitboard
-/// representing all squares along the line in front of the square, from the
-/// point of view of the given color. Definition of the table is:
-/// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
-inline Bitboard forward_bb(Color c, Square s) {
- return ForwardBB[c][s];
-}
+// distance() functions return the distance between x and y, defined as the
+// number of steps for a king in x to reach y.
+
+template<typename T1 = Square>
+inline int distance(Square x, Square y);
+template<>
+inline int distance<File>(Square x, Square y) {
+ return std::abs(file_of(x) - file_of(y));
+}
-/// passed_pawn_mask takes a color and a square as input, and returns a
-/// bitboard mask which can be used to test if a pawn of the given color on
-/// the given square is a passed pawn. Definition of the table is:
-/// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
+template<>
+inline int distance<Rank>(Square x, Square y) {
+ return std::abs(rank_of(x) - rank_of(y));
+}
-inline Bitboard passed_pawn_mask(Color c, Square s) {
- return PassedPawnMask[c][s];
+template<>
+inline int distance<Square>(Square x, Square y) {
+ return SquareDistance[x][y];
}
+inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
-/// attack_span_mask takes a color and a square as input, and returns a bitboard
-/// representing all squares that can be attacked by a pawn of the given color
-/// when it moves along its file starting from the given square. Definition is:
-/// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+// Returns the pseudo attacks of the given piece type
+// assuming an empty board.
+template<PieceType Pt>
+inline Bitboard attacks_bb(Square s) {
-inline Bitboard attack_span_mask(Color c, Square s) {
- return AttackSpanMask[c][s];
+ assert((Pt != PAWN) && (is_ok(s)));
+
+ return PseudoAttacks[Pt][s];
}
-/// squares_aligned returns true if the squares s1, s2 and s3 are aligned
-/// either on a straight or on a diagonal line.
+// Returns the attacks by the given piece
+// assuming the board is occupied according to the passed Bitboard.
+// Sliding piece attacks do not continue passed an occupied square.
+template<PieceType Pt>
+inline Bitboard attacks_bb(Square s, Bitboard occupied) {
+
+ assert((Pt != PAWN) && (is_ok(s)));
+
+ switch (Pt)
+ {
+ case BISHOP :
+ return BishopMagics[s].attacks[BishopMagics[s].index(occupied)];
+ case ROOK :
+ return RookMagics[s].attacks[RookMagics[s].index(occupied)];
+ case QUEEN :
+ return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
+ default :
+ return PseudoAttacks[Pt][s];
+ }
+}
-inline bool squares_aligned(Square s1, Square s2, Square s3) {
- return (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
- & ( SquareBB[s1] | SquareBB[s2] | SquareBB[s3]);
+// Returns the attacks by the given piece
+// assuming the board is occupied according to the passed Bitboard.
+// Sliding piece attacks do not continue passed an occupied square.
+inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
+
+ assert((pt != PAWN) && (is_ok(s)));
+
+ switch (pt)
+ {
+ case BISHOP :
+ return attacks_bb<BISHOP>(s, occupied);
+ case ROOK :
+ return attacks_bb<ROOK>(s, occupied);
+ case QUEEN :
+ return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
+ default :
+ return PseudoAttacks[pt][s];
+ }
}
-/// same_color_squares() returns a bitboard representing all squares with
-/// the same color of the given square.
+// Counts the number of non-zero bits in a bitboard.
+inline int popcount(Bitboard b) {
-inline Bitboard same_color_squares(Square s) {
- return Bitboard(0xAA55AA55AA55AA55ULL) & s ? 0xAA55AA55AA55AA55ULL
- : ~0xAA55AA55AA55AA55ULL;
-}
+#ifndef USE_POPCNT
+ union {
+ Bitboard bb;
+ uint16_t u[4];
+ } v = {b};
+ return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
-/// Functions for computing sliding attack bitboards. Function attacks_bb() takes
-/// a square and a bitboard of occupied squares as input, and returns a bitboard
-/// representing all squares attacked by Pt (bishop or rook) on the given square.
-template<PieceType Pt>
-FORCE_INLINE unsigned magic_index(Square s, Bitboard occ) {
+#elif defined(_MSC_VER)
- Bitboard* const Masks = Pt == ROOK ? RMasks : BMasks;
- Bitboard* const Magics = Pt == ROOK ? RMagics : BMagics;
- unsigned* const Shifts = Pt == ROOK ? RShifts : BShifts;
+ return int(_mm_popcnt_u64(b));
- if (Is64Bit)
- return unsigned(((occ & Masks[s]) * Magics[s]) >> Shifts[s]);
+#else // Assumed gcc or compatible compiler
- unsigned lo = unsigned(occ) & unsigned(Masks[s]);
- unsigned hi = unsigned(occ >> 32) & unsigned(Masks[s] >> 32);
- return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
+ return __builtin_popcountll(b);
+
+#endif
}
-template<PieceType Pt>
-inline Bitboard attacks_bb(Square s, Bitboard occ) {
- return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
+// Returns the least significant bit in a non-zero bitboard.
+inline Square lsb(Bitboard b) {
+ assert(b);
+
+#if defined(__GNUC__) // GCC, Clang, ICX
+
+ return Square(__builtin_ctzll(b));
+
+#elif defined(_MSC_VER)
+ #ifdef _WIN64 // MSVC, WIN64
+
+ unsigned long idx;
+ _BitScanForward64(&idx, b);
+ return Square(idx);
+
+ #else // MSVC, WIN32
+ unsigned long idx;
+
+ if (b & 0xffffffff)
+ {
+ _BitScanForward(&idx, int32_t(b));
+ return Square(idx);
+ }
+ else
+ {
+ _BitScanForward(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ }
+ #endif
+#else // Compiler is neither GCC nor MSVC compatible
+ #error "Compiler not supported."
+#endif
}
+// Returns the most significant bit in a non-zero bitboard.
+inline Square msb(Bitboard b) {
+ assert(b);
-/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
-/// pop_1st_bit() finds and clears the least significant nonzero bit in a
-/// nonzero bitboard.
+#if defined(__GNUC__) // GCC, Clang, ICX
-#if defined(USE_BSFQ)
+ return Square(63 ^ __builtin_clzll(b));
-#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
+#elif defined(_MSC_VER)
+ #ifdef _WIN64 // MSVC, WIN64
-FORCE_INLINE Square first_1(Bitboard b) {
- unsigned long index;
- _BitScanForward64(&index, b);
- return (Square) index;
-}
+ unsigned long idx;
+ _BitScanReverse64(&idx, b);
+ return Square(idx);
-FORCE_INLINE Square last_1(Bitboard b) {
- unsigned long index;
- _BitScanReverse64(&index, b);
- return (Square) index;
-}
-#else
+ #else // MSVC, WIN32
-FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
- Bitboard dummy;
- __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
- return (Square) dummy;
-}
+ unsigned long idx;
-FORCE_INLINE Square last_1(Bitboard b) {
- Bitboard dummy;
- __asm__("bsrq %1, %0": "=r"(dummy): "rm"(b) );
- return (Square) dummy;
-}
+ if (b >> 32)
+ {
+ _BitScanReverse(&idx, int32_t(b >> 32));
+ return Square(idx + 32);
+ }
+ else
+ {
+ _BitScanReverse(&idx, int32_t(b));
+ return Square(idx);
+ }
+ #endif
+#else // Compiler is neither GCC nor MSVC compatible
+ #error "Compiler not supported."
#endif
-
-FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
- const Square s = first_1(*b);
- *b &= ~(1ULL<<s);
- return s;
}
-#else // if !defined(USE_BSFQ)
+// Returns the bitboard of the least significant
+// square of a non-zero bitboard. It is equivalent to square_bb(lsb(bb)).
+inline Bitboard least_significant_square_bb(Bitboard b) {
+ assert(b);
+ return b & -b;
+}
-extern Square first_1(Bitboard b);
-extern Square last_1(Bitboard b);
-extern Square pop_1st_bit(Bitboard* b);
+// Finds and clears the least significant bit in a non-zero bitboard.
+inline Square pop_lsb(Bitboard& b) {
+ assert(b);
+ const Square s = lsb(b);
+ b &= b - 1;
+ return s;
+}
-#endif
+} // namespace Stockfish
-#endif // !defined(BITBOARD_H_INCLUDED)
+#endif // #ifndef BITBOARD_H_INCLUDED
projects / stockfish / blobdiff